This section provides background information related to the present disclosure which is not necessarily prior art.
U.S. Patent Application Publication No. 2010/0038164 discloses a vehicle with an all-wheel drive driveline with a disconnecting drive unit. More specifically, the all-wheel drive driveline includes a front differential, a power take-off unit, and a rear drive unit. The front differential is driven on a continuous basis to drive a pair of front vehicle wheels and provides rotary power to an input of the power take-off unit. The power take-off unit can provide rotary power to the rear drive unit to drive a pair of rear vehicle wheels. One or more clutches or couplings in each of the power take-off unit and the rear drive unit can be employed to selectively disconnect the output of the power take-off unit and the rear drive unit from the front differential to permit the driveline to be operated in a front wheel drive mode. Configuration of the driveline in this manner can be advantageous as it permits the driveline to be operated in an all-wheel drive (AWD) mode when those capabilities are desired, and to operate in a two-wheel drive (2WD) mode for better fuel economy when all-wheel drive capabilities are not desired.
It will be appreciated that it can be desirable to switch the operational mode of such disconnecting all-wheel drive drivelines between the AWD and 2WD modes during operation of a vehicle. Depending on the configuration of the vehicle powertrain (i.e., engine, transmission and torque converter) and the configuration of the driveline, it can be possible in some situations for the vehicle to generate noise when the operational mode of the driveline is changed from the AWD mode to the 2WD mode. Accordingly, there remains a need in the art for an improved method for operating a vehicle having an all-wheel driveline with a disconnecting drive unit.